annotate demo/url.ur @ 1886:b7cd3c7c7edd

Interpret 'table' signature items more flexibly, automatically adding (Ur) constraints to support a kind of subtyping over (SQL) constraint sets
author Adam Chlipala <adam@chlipala.net>
date Mon, 04 Nov 2013 15:14:23 -0500
parents 412ccd97ab71
children
rev   line source
adamc@774 1 fun yourChoice r = return <xml><body>
adamc@774 2 {case checkUrl r.Url of
adamc@774 3 None => <xml>You aren't allowed to link to there.</xml>
adamc@774 4 | Some url => <xml><a href={url}>Enjoy!</a></xml>}
adamc@774 5 </body></xml>
adamc@774 6
adamc@774 7 fun main () = return <xml><body>
adamc@774 8 <a href="http://en.wikipedia.org/wiki/Type_inference">Learn something</a><br/>
adamc@774 9 <br/>
adamc@774 10 <form>
adamc@774 11 URL of your choice: <textbox{#Url}/> <submit action={yourChoice}/>
adamc@774 12 </form>
adamc@774 13 </body></xml>